THE sky was a perfect Yankee blue yesterday. Whitey Ford and Yogi Berra were back on the lush green grass giving each other a familiar hug, and David Cone’s breaking ball was once again tantalizingly terrific. A championship aura was in the air. Remember, though, Yankee Stadium always has been known for its facade.

Look closely and it is clear this Yankee season will not be the post-season joy ride of the past two years. There are problems. The kind that can catch up to you in October. The air of invincibility is gone.

The Yankees were 3-3 on their last road trip and are 2-2 on this homestand after yesterday’s 5-4 loss to the Angels. Difficult losses despite an infusion of firepower the team has never had during Joe Torre’s reign. All the while, the Red Sox linger. The Yankees should have won all four games against the Angels, but twice the bullpen collapsed. It was a 3-0 lead that went poof after six shutout innings yesterday from Cone, who is showing that championship players do not go quietly.

In their two losses to Anaheim, the Yankees managed to blow eight runs of leads, That’s something that happens to the Twins, not the Yankees. A five-run ninth-inning bulge was lost Friday night. The relievers can’t throw strikes at critical times. Three of the Angels’ five runs yesterday reached base on walks. Torre has lost confidence in Jeff Nelson and has not regained total confidence in Cone. Mike Stanton has surrendered two critical home runs his last two outings and yesterday walked the first batter he faced, the same as Nelson.

Afterwards, the befuddled Nelson sat at his locker and looked like a pitcher about to get voted off the island. “Somewhere, it’s in the back of your mind that you’ve got to be perfect or you’re going to get pulled again,” Nelson said.

Bernie Williams missed his second straight game with the kind of rib injury that can linger – in 1993 the pain lasted a month – Chuck Knoblauch remains in Tampa, fighting back from a sore elbow and Tino Martinez continues to show a slow bat.

And it’s not as if opposing pitchers are throwing the ball as fast as Al Gore’s son drives. The Angels tossed some gak at the Yankees this series.

Jerry Coleman was one of the proud, old Yankees who came back to honor Whitey. The second baseman won six World Championships in pinstripes. He would have won more, but flew 120 missions as a Marine pilot in World War II and Korea. Like Whitey, he gave some of the best years of his life to his country. That, of course, is something this generation of ballplayers does not have a clue about. Imagine such spoiled children as Ken Griffey Jr. having to go fight for their country.

“Whitey, at a young age, was a more mature pitcher than anybody I ever saw,” Coleman said. “Even Koufax took seven years to find out where he was. Whitey went 9-1 as a 21-year-old kid, a rookie, he came out of the minor leagues and took us to the pennant in 1950. He pitched the critical game against Detroit. he was just a tremendous clutch guy. Pitching dominates and we had great pitching that year and everybody hit .300, except me.”

Having said all that, it’s obvious Coleman knows his pitching and this is what he said of the Yankees’ staff. “Their pitching has fallen off from a few years ago,” noted the Padre broadcaster, whose team was swept away by the Yankees in the 1998 World Series. “Cone has had a tough year and he is so important to them. El Duque is struggling and even (Mariano) Rivera isn’t closing them out like he was the last two years.”

Pitching, of course, is the most difficult of baseball chores, especially today. Ford admitted he would have his problems with Bud Selig’s video-game version of Major League Baseball 2000. “I think with the artificial turf, with the ball, it could be livelier, and they’re building some smaller ballparks,” Ford said. “I think I could pitch now, but I don’t think my earned run average (2.75) would have been as low. My winning percentage probably would have been the same, but it’s a little tougher pitching today.”

Hernandez goes today against the Rangers and will be watched closely like Cone. In his effort to nurse Cone back to pitching health, Torre erred on the side of caution yesterday, removing his right-hander with a shutout and only 96 pitches in the books. Torre didn’t expect his bullpen to walk away the lead.

“Baseball has been around a long time,” Torre said, “and that is the one thing that has always baffled and frustrated managers – the fact that you walk people and there is no defense for that and it came back to haunt us today. We need to straighten it out.”

That’s not all the Yankees need to straighten out over the next six weeks.